Hose clamps/jubilee clips are a streamlined way to rig sidemount tanks. For brevity, I will be referring to them as hose clamps from now on. Hose clamps are less bulky than cam bands and can also be quite sturdy. In some scenarios, cam bands can have their merits though, e.g. when a lot of tank swaps are required.
Once you have decided to use hose clamps, the next question that arises is which one? A good hose clamp must be mechanically strong and saltwater corrosion resistant. BoatUS took a closer look at what criteria hose clamps need to meet in saltwater environments in their article “All About Hose Clamps”.
- Key requirements for good hose clamps:
- High corrosion resistance (minimum AISI 316L)
- Embossed band
- One piece worm drive housing
- Solid hex screw
- High torque mechanism
- Recommended product: ABA Original SMO S60 hose clamps
The available stainless-steel grades differ significantly in their corrosion resistance and other properties. Some cheaper varieties may withstand freshwater but not saltwater.
The steel used is decisive for a clamp’s resistance to pitting corrosion and the overall quality and longevity of the product. Many clamps found in dive shops and hardware stores are manufactured from AISI 304 stainless steel, which is a lesser grade that does not contain molybdenum and is thus more corrosion-prone (see Figure 1). AISI 316 (without the L steel is also often available. AISI 316 has a comparatively high carbon content, which promotes the formation of chromium carbides. These chromium carbides can lead to intergranular corrosion. Any use in saltwater thus requires a low carbon content. AISI 304 and 306 stainless steels should be considered unsuitable for use in diving equipment.
Another aspect to consider is that sometimes the clamp’s components are made of different materials. Such clamps should also be rejected. You should not buy hose clamps from local dive shops, hardware stores, or chandlers unless you can verify the brand and exact type including the steel used throughout the clamp.
Pitting Resistance Equivalent (PRE, PREN) Number
Predicts the pitting corrosion resistance of stainless steels based on their chemical composition. A higher number indicates a higher level of corrosion resistance.
Critical Pitting Temperature (CPT) or Critical Crevice Temperature (CCT)
The lowest temperature at which a metal surface starts to pit.
High temperatures can have a detrimental effect on the corrosion behavior of stainless steel. In other words: The warmer the water, the more corrosion resistant stainless steel needs to be to withstand rusting, i.e. a higher CPT indicates higher corrosion resistance. The table below lists material properties of AISI 304 and 316 steel.
| EN Steel Number (Europe) | 1.4301 | 1.4401 |
|---|---|---|
| AISI | 304 | 316 |
| Tensile strength N/mm² | 500-700 | 500-700 |
| PREN | 17,5-21,1 | 24 |
| CPT in °C | 10 | 20 |
Hose clamps made of stainless steel with the material designation 1.4404 (AISI 316L) are a better choice for hose clamps and should be considered the minimum material grade. Compared to AISI 316, AISI 316L has a lower carbon content, which positively affects corrosion resistance. This is denoted by the letter “L” at AISI. The “L” stands for “Low Carbon”.
For use in temperate and tropical waters, steels with even higher levels of corrosion resistance are recommended (see table below). For this table, stainless-steel grades were chosen that are used in high-quality anchor chains – with the exception of AISI 254 SMO. Not all of these steel grades are available as hose clamps though. Only AISI 316L and AISI 254 SMO hose clamps are available at the time of writing.
| EN steel number (Europe) | 1.4404 | 1.4462 | 1.4507 | 1.4547 |
|---|---|---|---|---|
| AISI | 316L | 318LN Duplex | F255 Superduplex | 254 SMO |
| Tensile strength N/mm² | 510-710 | 650-880 | ≥760 | 650–850 |
| PREN | 23,1-28,5 | 30,85-38,07 | 37-44 | ≥42,5 |
| CPT in °C | 24-27,5 | 27,5-34,5 | >70 | >90 |
Hose clamps may either have a perforated band, where the thread is stamped out, or be embossed. Embossed bands are better since the thread is formed on the clamp band without the need for holes. Hose clamps with perforated bands should be avoided because the holes reduce the clamp’s mechanical strength and offer a place for corrosion to start. These issues can be avoided by using embossed bands.
Practical Sailor performed a long-term corrosion resistance test of hose clamps in 2014. The hose clamps by ABA came out on top. In contrast to the other clamps tested, this product remained untarnished and mechanically intact even after being submerged in a saltwater bath for eighteen months. The ABA product tested was made of 316 stainless-steel and featured an embossed clamp band. However, for diving applications, a higher steel grade than AISI 316 is advisable since divers often encounter tropical water temperatures, which can quickly overwhelm the corrosion resistance of 316 steel.
ABA also offers even more corrosion resistant hose clamps made of AISI 254 SMO stainless steel (Figure 2). These are designed for the most extreme environments. AISI 254 SMO steel is designed for corrosive environments and can withstand thousands of hours submerged in saltwater. The underside of the band is smooth, and the worm drive housing is manufactured from one piece; compare to the two-piece worm drive housing of the hose clamp depicted in Figure 1. In contrast to many other hose clamps, this type requires a 7mm hex key since the hexagonal screw is one solid piece without a slit for a Philips screwdriver. This adds to its mechanical strength.
Suitable clamping ranges for some commonly used tanks are listed in the table below.
| Tank type | 12 l light steel | 80 cu ft aluminum | 7 l aluminum |
| Tank diameter in mm | 171 | 184 | 152 |
| Suitable clamping range in mm | 150-180 | 175-205 | 130-165 |
To cover the protruding band, 20mm wide textile hose can be used (see Figure 3). The housing can be covered with 25mm textile hose, e.g. made of dyneema. Covering any part of the clamp in rubber hose is not recommended as it makes rinsing and drying of the clamp’s parts difficult.
